According to the provisional results of 2011 national census, West Bengal is the fourth most populous state in India with a population of 91,347,736 (7.55% of India's population). Majority of the population comprises Bengalis. The Marwaris, Bihari and Oriya minority are scattered throughout the state; communities of Sherpa's and ethnic Tibetans can be found in Darjeeling Himalayan hill region. Darjeeling district has a large number of Gurkha people of Nepalese origin. West Bengal is home to indigenous tribal Adivasis such as Santals, Kol, Koch-Rajbongshi and Toto tribe. There are a small number of ethnic minorities primarily in the state capital, including Chinese, Tamils, Gujaratis, Anglo-Indians, Armenians, Punjabis, and Parsis. India's sole Chinatown is in eastern Kolkata.

The official language is Bengali and English. Nepali is the official language in three subdivisions of Darjeeling district. As of 2001, in descending order of number of speakers, the languages of the state are: Bengali, Hindi, Santali, Urdu, Nepali, and Oriya. Languages such as Rajbongshi and Ho are used in some parts of the state.

As of 2001, Hinduism is the religion at 72.5% of the total population, while Muslims comprise 25.2% of the total population , being the second-largest community as also the largest minority group; Sikhism, Christianity and other religions make up the remainder. The state contributes 7.8% of India's population. The state's 2001–2011 decennial growth rate was 13.93%, lower than 1991–2001 growth rate of 17.8%, and also lower than the national rate of 17.64%. The gender ratio is 947 females per 1000 males. As of 2011, West Bengal has a population density of 1,029 inhabitants per square kilometer (2,670 /sq mi) making it the second-most densely populated state in India, after Bihar.

The literacy rate is 77.08%, higher than the national rate of 74.04%. Data of 1995–1999 showed the life expectancy in the state was 63.4 years, higher than the national value of 61.7 years. About 72% of people live in rural areas. The proportion of people living below the poverty line in 1999–2000 was 31.9%. Scheduled Castes and Tribes form 28.6% and 5.8% of the population respectively in rural areas, and 19.9% and 1.5% respectively in urban areas. This is the fourth-lowest crime rate among the 28 states and 7 union territories of India. West Bengal was the first Indian state to constitute a Human Rights Commission of its own.